1. Field of the Invention
The present invention relates to drive mechanisms for bicycles. This invention more particularly pertains to a hydraulic drive mechanism to propel a bicycle.
2. Description of the Background Art
Presently, most commercially available bicycles utilize a drive chain about a chain ring, driven by a crank axle and pedals, and a rear section gear cluster which is attached to the hub of the rear wheel to transmit power from the manually operated pedals to the rear wheel of the bicycle. For multi-speed bicycles, front and rear chain deraileurs cooperate with each other and in conjunction with a tensioning wheel to shift the drive chain from gear sprockets of varying diameters which results in the bicyclist being able to rotate the pedals at varying rates.
However, many hydraulic driven bicycles are known. For example, U.S. Pat. No. 4,249,750 to Kantner discloses a combination pump and motor for a hydraulic driven bicycle. Each pump and motor includes a plurality of fluid-pressure zones wherein one is a low pressure zone and another is a high pressure zone. Rotators in contact with one another, wherein one rotator has a smooth surface and another has a gear-like surface, transfer fluid from one zone to another zone. The rotators are arranged so that adjacent rotators are in contact and create a fluid-displacement path at the interface therebetween adjacent rotators. The Kantner patent discloses rotators in the pump having a 1:1 relationship with the rotators in the motor.
U.S. Pat. No. 4,688,815 to Smith teaches a hydraulic driven bicycle driven by a hydraulic pump and a hydraulic drive mechanism. The hydraulic pump has a pump chamber that may be varied in size for varying the flow of fluid through the pump mechanism. The drive mechanism has a drive chamber that also may be varied in size for varying the flow of fluid through the drive mechanism. However, this reference does not disclose a hydraulic drive means for propelling bicycles as disclosed by the present invention.
U.S. Pat. No. 4,290,621 to Davey discloses a bicycle employing a hydraulic multi-speed drive mechanism comprising a multi-chambered pump and a multi-chambered motor wherein selection of each chamber controls the amount of passing fluid and, hence, the speed of the bike is affected. Moreover, the patent to Davey discloses how to permit removal of the rear wheel from the bicycle without interrupting the hydraulic circuit. However, the present inventor believes the bicycle disclosed in the patent to Davey could not possibly work effectively because of the dimensional characteristics affecting the transmission of hydraulic fluid and, ultimately, the rotary motion of the complete hydraulic drive mechanism.
In response to these earlier hydraulic driven bicycles, it became clear that there is a need for an improved hydraulic drive mechanism. This device must provide for a smooth transition from a resting position to high speed without the usual shifting of gears as is encountered on conventional multi-speed bicycles.
In as much as the art consists of various types of bicycles, it can be appreciated that there is a continuing need for and interest in improvements to hydraulic driven bicycles, and in this respect, the present invention addresses these needs and interests.
Therefore, the principal object of this invention is to provide an improvement which overcomes the inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of hydraulic driven bicycles.
Another object of this invention is to provide a new and improved hydraulic drive means for bicycles which has all the advantages and none of the disadvantages of the earlier hydraulic driven bicycles.
Still another objective of the present invention is to provide a hydraulic bicycle that is lightweight and easily ridden.
Yet another objective of the present invention is to provide a hydraulic bicycle that is easily manufactured and assembled.
Still a further objective of the present invention is to provide a hydraulic bicycle capable of a smooth transition from a stationary position to a higher speed without the usual shifting of gears.
Yet a further objective is to provide a hydraulic drive mechanism that requires minimal maintenance for the biker.
An additional objective is to provide a pump that is powered by the conventional pedal and brake arrangement.
Another objective is to provide a drive mechanism for a bicycle having a frame comprising of a seat tube, seat stay and chain stay, a pedal means for applying manual power to propel the bicycle, a drive wheel rotatably supported on the frame, and a drive mechanism connected to the pedal means for rotating the drive wheel, an improved drive mechanism comprising a pump unit comprising a pump housing, a first gear assembly operationally disposed within the pump housing and driven by the rotation of the pedal means outside of the pump housing, the pump unit outwardly adjacent the seat tube and the chain stay; a hydraulic motor being supported on the frame, the hydraulic motor comprising a motor housing and a second gear assembly operationally disposed within the motor housing, the second gear assembly adapted to engage the drive wheel, the hydraulic motor outwardly adjacent the seat stay and the chain stay and driven by the hydraulic fluid pumped by the pump unit, the pump unit and the hydraulic motor having a rotary motion relationship in the range of approximately 2.5:1 up to approximately 18:1; conduit means coupled between the hydraulic motor and the pump unit for circulating hydraulic fluid through the pump unit and the hydraulic motor, the conduit means creating a closed hydraulic system; pressure regulator means in the closed hydraulic system for controlling the quantity of hydraulic fluid transmitted to the hydraulic motor when the pedal means is rotated; and a hydraulic fluid reservoir disposed above the pump unit, the conduit means coupled to and in fluid communication with the reservoir.
Even yet another objective is to provide a drive mechanism for a bicycle having a frame comprising of a seat tube, seat stay and chain stay, a pedal means for applying manual power to propel the bicycle, a drive wheel rotatably supported on the frame, and a drive mechanism connected to the pedal means for rotating the drive wheel, an improved drive mechanism comprising a pump unit comprising a pump housing and a first gear assembly, the first gear assembly comprising a pump idler gear and pump bull gear in rotational meshing contact with one another and operationally disposed within the pump housing, the pump bull gear driven by the rotation of the pedal means outside of the pump housing, the pump unit outwardly adjacent the seat tube and the chain stay; a hydraulic motor being supported on the frame, the hydraulic motor comprising a motor housing and a second gear assembly, the second gear assembly comprising a smaller pinion gear and a larger idle gear in rotational meshing contact with one another and operationally disposed within the motor housing, the smaller pinion gear adapted to engage the drive wheel, the hydraulic motor outwardly adjacent the seat stay and the chain stay and driven by the hydraulic fluid pumped by the pump unit, the pump unit and the hydraulic motor having a rotary motion relationship configured by varying combinations of the first and second gear assemblies, the first and second gear assemblies having teeth meshing together to form inter-tooth pockets, the inter-tooth pockets facilitating hydraulic fluid transfer, the teeth of the first and second gear assemblies having a face width and a whole depth defining approximately a 12:1 rotary motion relationship; a conduit means for transmitting hydraulic fluid from the pump unit to the hydraulic motor and returning the hydraulic fluid from the hydraulic motor to the pump unit, the conduit means comprising of a small diameter conduit line for transmitting hydraulic fluid from the pump unit and a large diameter conduit line for returning hydraulic fluid from the hydraulic motor, the conduit means creating a closed hydraulic system; pressure regulator means for controlling the quantity of hydraulic fluid transmitted to the hydraulic motor when the pedal means is rotated, the pressure regulator means comprising a hydraulic fluid bypass in the pump unit, the hydraulic fluid bypass having a spring-loaded plunger interposed in the bypass; and a hydraulic fluid reservoir disposed within the seat tube and above the pump unit, the large diameter conduit line having a first end coupled to the reservoir and in fluid communication with the reservoir.
The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a more comprehensive understanding of the invention may be obtained by referring to the summary of the invention, and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.